Locking unit for a device for modifying the timing of charge change valves in internal combustion engines, especially for a vane-cell control device

ABSTRACT

The invention relates to a locking unit for a device for modifying the timing of charge change valves of an internal combustion engine, especially for a vane-cell control device. Said device ( 1 ) comprises a drive wheel ( 3 ) presenting a hollow space ( 8 ) and connected to a crankshaft of the internal combustion engine in a driving manner. The device also comprises an impeller ( 9 ) which has at least one vane ( 13 ) and is connected to the camshaft ( 2 ) in a non-rotating manner. At least one working chamber ( 20 ), which is divided by a vane ( 13 ) into two hydraulic pressure chambers ( 21, 22 ), is formed by intermediate walls ( 16 ) in the hollow space ( 8 ) of the drive wheel ( 3 ). When the pressure chambers ( 21, 22 ) are subjected to pressure by means of a hydraulic pressure medium they cause the impeller ( 9 ) to pivot in relation to the drive wheel ( 3 ). When there is no pressure in one of the two pressure chambers ( 21, 22 ) the impeller ( 9 ) and the drive wheel ( 3 ) are mechanically coupled to each other. According to the invention the mechanical coupling between the impeller ( 9 ) and the drive wheel ( 3 ) of the device ( 1 ) can be achieved by means of at least one radially movable vane ( 13 ) of the impeller ( 9 ) which is configured as both an impeller pivoting element and a locking element.

This application is a 371 of PCT/EP98/07466 filed Nov. 20, 1998.

FIELD OF THE INVENTION

The invention concerns a locking device for a device for varying valvetiming of gas exchange valves of an internal combustion engine,particularly for a vane-type adjusting device, said locking devicecomprising a drive pinion configured as an outer rotor and connected indriving relationship to a crankshaft of the internal combustion engineby a traction means, said drive pinion having a hollow space defined bya circumferential wall and two side walls, and a winged wheel insertedinto this hollow space and configured as an inner rotor which isconnected rotationally fast to a camshaft of the internal combustionengine, said winged wheel comprising on the periphery of its wheel hubat least one wing that is arranged in an axial groove and extendsradially away from the wheel hub, at least one working chamber beingdefined within the hollow space of the drive pinion by intermediatewalls that start from the inner surface of the circumferential wall ofthe drive pinion and extend toward the central longitudinal axis of thedevice, said working chamber being divided by a wing of the winged wheelextending in each working chamber into two hydraulic pressure chamberswhich, by an optional successive or simultaneous pressurizing by ahydraulic pressure medium, effect a turning and/or fixing of the wingedwheel relative to the drive pinion, while in the absence of pressureloading of one of the pressure chambers, the winged wheel and the drivepinion can be coupled to each other mechanically in at least onepreferred position.

BACKGROUND OF THE INVENTION

A generic device of the pre-cited type is known from U.S. Pat. No.4,858,572. In a preferred embodiment of this device, six equally largeworking chambers are formed in the hollow space of the drive pinionbetween six circumferentially opposed intermediate walls. These sixworking chambers are divided into fluid-tight first and second pressurechambers by six wings rigidly connected to the hub of a winged wheelwhich is connected to the camshaft. The mechanical coupling between thewinged wheel and the drive pinion of the device is accomplished by aspring-loaded locking pin arranged in a radial bore of one of theintermediate walls. This locking pin engages a reception bore arrangedbetween two wings in the hub when the wings of the winged wheel abut inan end position against the intermediate walls of the drive pinion andthe first pressure chambers of the device are cut off from thepressurization by the hydraulic pressure medium. When, upon a renewedpressurization of these pressure chambers, the hydraulic medium pressureexceeds a set value, the locking pin is displaced against the force ofits spring entirely out of the reception bore in the hub into the radialbore in the intermediate wall so that the mechanical coupling betweenthe winged wheel and the drive pinion is released. When, after arelative rotation between the winged wheel and the drive pinion, thewings are brought into abutment in their opposite end position againstthe intermediate walls of the drive pinion, and the second pressurechambers of the device are cut off from the pressurization by thehydraulic pressure medium, a second mechanical coupling between thewinged wheel and the drive pinion is effected by a locking pin similarlyarranged in another intermediate wall. This locking action is likewiseundone when a defined pressure medium pressure in the second pressurechambers is exceeded.

A mechanical coupling of this type between the winged wheel and thedrive pinion, however, has the drawback that it is formed by a pluralityof additional separate components which in view of the extra expensesfor their fabrication and assembly disadvantageously increase themanufacturing costs of such a vane-type adjusting device. Also, due tothe configuration of the locking pins as simple pressure pins, thereexists the possible drawback that the locking pins be deformed when theyhave been subject to high stresses acting in both directions of rotationso that a continued, satisfactory locking of the device is then notalways guaranteed.

OBJECT OF THE INVENTION

The object of the invention is therefore to conceive a locking devicefor a device for varying the valve timing of gas exchange valves of aninternal combustion engine, particularly for a vane-type adjustingdevice, which locking device should comprise the smallest possiblenumber of separate components so that its manufacturing and assemblycosts are low, and said locking device must guarantee a continued,satisfactory locking of the adjusting device even after taking up highstresses in both directions of rotation.

SUMMARY OF THE INVENTION

In accordance with the invention, this object is achieved with a devicefor varying valve timing of gas exchanqe valves of an internalcombustion engine, particularly for a vane-type adjusting device, saidlocking device comprising a drive pinion (3) configured as an outerrotor and connected in driving relationship to a crankshaft of theinternal combustion engine by a traction means, said drive pinion havinga hollow space (8) defined by a circumferential wall (4) and two sidewalls (6,7), and a winged wheel (9) inserted into this hollow space (8)and configured as an inner rotor which is connected rotationally fast toa camshaft (2) of the internal combustion engine, said winged wheel (9)comprising on the periphery (10) of its wheel hub (11) at least one wing(13) that is arranged in an axial groove (12) and extends radially awayfrom the wheel hub (11), at least one working chamber (20) being definedwithin the hollow space (8) of the drive pinion (3) by intermediatewalls (16) that start from the inner surface (5) of the circumferentialwall (4) of the drive pinion (3) and extend toward the centrallongitudinal axis of the device (1), said working chamber (20) beingdivided by a wing (13) of the winged wheel (9) extending in each workingchamber (20) into two hydraulic pressure chambers (21, 22) which, by anoptional successive or simultaneous pressurizing by a hydraulic pressuremedium, effect a tuning and/or fixing of the winged wheel (9) relativeto the drive pinion (3), while in the absence of pressure loading of oneof the pressure chambers (21 or 22), the winged wheel (9) and the drivepinion (3) can be coupled to each other mechanically in at least onepreferred position. By the fact that the mechanical coupling between thewinged wheel and the drive pinion of the device can be established by atleast one wing of the winged wheel, which wing is configured both as apivoting element of the winged wheel and as a locking element which canbe arrested in a locking position on the drive pinion by an auxiliaryenergy when a pressure of the hydraulic pressure medium falls short of apressure required for pivoting the winged wheel, and which can bearrested in a releasing/pivoting position within its associated workingchamber when a defined value of hydraulic pressure medium pressure isexceeded.

According to a further advantageous feature of the invention, each wingof the winged wheel configured as a locking element is arranged forradial movement within its axial groove in the wheel hub of the wingedwheel, and a free end of said wing is in positive engagement with acorresponding axial fixing groove in the inner surface of thecircumferential wall of the drive pinion in one or more lockingpositions of the device. Each axial fixing groove preferably extendsover the entire width of the inner surface of the circumferential wallof the drive pinion, and a width of the axial fixing groove is such thatthe wing concerned can slip easily into said axial fixing groove while,at the same time, a rattling of the wing in its locking position isprevented.

It has proved to be particularly economic to configure only one wing ofthe winged wheel as a locking element irrespective of the number ofwings present. This one wing is then in locking connection only in oneof its end positions with an axial fixing groove which directly adjoinsone of the two intermediate walls that define its working chamber orpressure chambers. However, the scope of the invention also includessolutions in which two or more wings are configured as locking elementswhich can be locked either in one of their end positions or, byarranging a further axial fixing groove on the second intermediate wallin each working chamber, even in both their end positions. It is equallypossible to configure one or more of the wings for locking in one of theend positions and one or more wings for locking in the other endposition of the wings and/or, by arranging further axial fixing groovesin the working chambers, to fix the winged wheel in one or morepositions between the end positions if this is required for certainoperating conditions of the internal combustion engine.

According to a further feature of the locking device of the invention,it is proposed to produce the auxiliary energy required for locking thewing in its locking position by spring means supported at one end on thegroove bottom of the axial groove of the wheel hub and at the other endon the hub-proximate end of the wing. It has proved to be particularlyadvantageous to make the spring means as a leaf spring of spring steeland to insert it in longitudinal direction into the axial groove of thewing that is configured as a locking element. However, it is alsopossible to produce the auxiliary energy by coiled pressure springs orother suitable spring means let into the groove bottom of the axialgroove and into guide bores in the hub-proximate end of the wing.

According to another feature of the invention, the free end of the wingconfigured as a locking element is slightly chamfered in radialdirection and configured as a pressure-application surface for thehydraulic pressure medium for the unlocking position of the wing. Aseparate pressure medium supply duct opens into the widened gap thusformed between the free end of the wing and the groove bottom of theaxial fixing groove and communicates with the pressure medium supplyduct of the pressure chamber of the working chamber containing the axialfixing groove. In a preferred embodiment, the separate pressure mediumsupply duct to the free end of the wing is configured in the drivepinion as an edge bevel on one of the two lateral edges of theintermediate wall adjoining the axial fixing groove and defining thepressure chamber. When this pressure chamber is pressurized, thehydraulic pressure medium acts at first along this edge bevel and,confined by the locked wing and one of the side walls of the drivepinion, on the chamfered free end of the wing. When a defined pressuremedium pressure is exceeded, the hydraulic pressure medium displaces thewing against its auxiliary energy into its unlocking position. It isonly after this that the pressure medium can bring about a change in thevolume of the pressure chamber and thus effect a rotation of the wingedwheel relative to the drive pinion. In an alternative embodiment,however, it is also possible to configure the separate pressure mediumsupply duct to the free end of the wing as a pressure medium guidegroove on the inner surface of one of the two side walls of the drivepinion. This guide groove is arranged at the level of and parallel tothe lateral surface of the intermediate wall adjoining the axial fixinggroove and defining the pressure chamber. The action of the guide grooveis similar to that of the aforesaid edge bevel.

Thus, the locking device of the invention for a vane-type adjustingdevice for varying the valve timing of gas exchange valves of aninternal combustion engine has the advantage over known locking devicesthat, due to the simultaneous use of a wing of the winged wheel both asa pivoting and a locking element, only a minimum of additionalindividual elements or work steps is required for realizing a locking ofthe winged wheel relative to the drive pinion in one or more positions.Thus, the locking device of the invention contrasts advantageously withknown locking devices by an enormous economy of material and productionsteps, so that the manufacturing costs of a vane-type adjusting devicecomprising such a locking device are only unsubstantially higher thanthose of a vane-type adjusting device having no locking device.Furthermore, the locking device of the invention possesses a high degreeof operating reliability with regard to the accommodation of highstresses in both directions of rotation because the wing which functionsas a locking element is locked over its entire width in a fixing groovethat likewise extends over the entire width of the circumferential wallof the drive pinion so that the locking element possesses theforce-supporting capacity which is required for assuring a stable andreliable locking.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described more closely with reference to anexample of embodiment illustrated in the appended drawings in which:

FIG. 1 is a top view of a vane-type adjusting device having a lockingdevice of the invention, with removed housing side wall;

FIG. 2 is a side view of a vane-type adjusting device along thesectional line A—A of FIG. 1;

FIG. 3 is a top view of a wing of the winged wheel configured accordingto the invention as a locking element, showing one embodiment of thepressure medium supply to the free end of the wing along the sectionalline B—B of FIG. 1;

FIG. 4 shows the view X of FIG. 3 of the inner surface of a side wall ofthe drive pinion with another embodiment of the pressure medium supplyto the free end of a wing of the winged wheel configured according tothe invention as a locking element;

FIG. 5 shows a section taken along line C—C of FIG. 4.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 clearly shows a device 1 configured as a vane-type adjustingdevice for varying the valve timing of gas exchange valves of aninternal combustion engine, said device comprising a drive pinion 3configured as an outer rotor and connected in driving relationship to acrankshaft, not shown, of the internal combustion engine by a tractionmeans, and a winged wheel 9 configured as an inner rotor which isconnected rotationally fast to a camshaft 2 of the internal combustionengine. FIGS. 1 and 2 further show that the drive pinion 3 comprises ahollow space 8 defined by a circumferential wall 4 and two side walls 6and 7, in which hollow space 8, four working chambers 20 are defined byfour intermediate walls 16 starting from the inner surface 5 of thecircumferential wall 4 and extending towards the central longitudinalaxis of the device 1. The winged wheel 9 is inserted into this hollowspace 8 and comprises on the periphery 10 of its wheel hub 11, fourwings 13, each of which is arranged in an axial groove 12 and extendsradially away from the wheel hub 11. Each wing 13 extends in one of thefour working chambers 20 of the drive pinion 3 and divides this workingchamber into two hydraulic pressure chambers 21, 22. Thus, by anoptional successive or simultaneous pressurizing of these pressurechambers 21, 22 by a hydraulic pressure medium, a pivoting and/or fixingof the winged wheel 9 relative to the drive pinion 3 can be realized, sothat the camshaft 2 pivots and/or is hydraulically fixed relative to thecrankshaft of the internal combustion engine in a manner, known per se.

Since the device 1 is in a virtually pressureless state when theinternal combustion engine is started, the alternating torques of thecamshaft 2 lead to a high-frequency abutment of the wings 13 of thewinged wheel 9 against the intermediate walls 16 of the drive pinion 3which results in an undesired generation of noise. The device of theinvention that establishes a mechanical coupling, known per se, betweenthe winged wheel 9 and the drive pinion 3 prevents such a noisegeneration by the fact that at least one wing 13 of the winged wheel 9is configured both as a pivoting element of the winged wheel and as alocking element which, when the pressure of the hydraulic pressuremedium falls short of a pressure required for pivoting the winged wheel9 can be arrested in a locking position on the drive pinion 3 by theaction of an auxiliary energy, and when the pressure of the hydraulicpressure medium exceeds a defined pressure, said locking element can bearrested in an unlocking/pivoting position within its associated workingchamber 20.

It can be seen in FIG. 1 that only one of the four wings 13 of thewinged wheel 9 is configured as a locking element in that this wing 13is arranged for radial displacement in its axial groove 12 in the wheelhub 11 of the winged wheel 9 while its free end 14 is in positiveengagement with an axial fixing groove 23 in the inner surface 5 of thecircumferential wall 4 of the drive pinion 3. In the present embodimentof the invention, this axial fixing groove 23 is arranged immediatelyadjoining the intermediate wall 16 which defines the working chamber 20,or pressure chamber 21, so that the wing 13 can be arrested on the drivepinion 3 only in one of its end positions, in the present case, in thestart position of the camshaft 2 which is favorable for starting theinternal combustion engine. The auxiliary energy required for arrestingthe wing 13 in its locking position is produced by a spring means 24 inthe form of a leaf spring, only schematically represented in FIG. 1,which is supported at one end on the groove bottom of the axial groove12 in the wheel hub 11, and at the other end on the hub-proximate end 15of the wing 13.

For releasing the device 1 from its locking position, i.e. for returningthe wing 13 into its unlocking position, the invention further providesthat the free end 14 of the wing 13, as generally shown in FIG. 1, isslightly chamfered in radial direction and configured as apressure-application surface for the hydraulic pressure medium. Aseparate pressure medium supply duct 25 opens into the widened gap thusformed between the free end 14 of the wing 13 and the groove bottom ofthe axial fixing groove 23 and communicates with the pressure mediumsupply duct 26 of the pressure chamber 21 of the working chamber 20 inwhich the axial fixing groove 23 is arranged. In a first embodimentrepresented in FIGS. 1 to 3, this separate pressure medium supply duct25 is configured in the drive pinion 3 as an edge bevel on one of thelateral edges 17, 18 of the intermediate wall 16 defining the pressurechamber 21. Said supply duct 25 is further defined by the locked wing 13and by one of the side walls 6, 7 of the drive pinion 3 so that it has atriangular cross-section through which the hydraulic pressure mediumfrom the pressure medium supply duct 26 can be transported to the freeend 14 of the wing 13. In an alternative embodiment shown in FIGS. 4 and5, the separate pressure medium supply duct 25 to the free end 14 of thewing 13 can be configured, for example, as a pressure medium guidegroove on the inner surface of the side wall 6 of the drive pinion 3 andis arranged at the level of and parallel to the lateral surface 19 (FIG.3) of the intermediate wall 16 adjoining the axial fixing groove 23 anddefining the pressure chamber 21 while itself being closed on its openside by this intermediate wall 16.

What is claimed is:
 1. A locking device for a device for varying valvetiming of gas exchange valves of an internal combustion engine,including for a vane-type adjusting device, said locking devicecomprising a drive pinion (3) configured as an outer rotor and connectedin driving relationship to a crankshaft of the internal combustionengine by a traction means, said drive pinion having a hollow space (8)defined by a circumferential wall (4) and two side walls (6, 7), and awinged wheel (9) inserted into this hollow space (8) and configured asan inner rotor which is connected rotationally fast to a camshaft (2) ofthe internal combustion engine, said winged wheel (9) comprising on theperiphery (10) of its wheel hub (11) at least one wing (13) that isarranged in an axial groove (12) and extends radially away from thewheel hub (11), at least one working chamber (20) being defined withinthe hollow space (8) of the drive pinion (3) by intermediate walls (16)that start from the inner surface (5) of the circumferential wall (4) ofthe drive pinion (3) and extend toward the central longitudinal axis ofthe device (1), said working chamber (20) being divided by a wing (13)of the winged wheel (9) extending in each working chamber (20) into twohydraulic pressure chambers (21, 22) which, by an optional successive orsimultaneous pressurizing by a hydraulic pressure medium, effect aturning or fixing of the winged wheel (9) relative to the drive pinion(3), while in the absence of pressure loading of one of the pressurechambers (21 or 22), the winged wheel (9) and the drive pinion (3) canbe coupled to each other mechanically in at least one preferredposition, characterized in that a mechanical coupling between the wingedwheel (9) and the drive pinion (3) of the device (1) is established byat least one wing (13) of the winged wheel (9), which wing (13) isconfigured both as a pivoting element of the winged wheel (9) and as alocking element which is arrested in a locking position on the drivepinion (3) when a pressure of the hydraulic pressure medium falls shortof a pressure required for pivoting the winged wheel (9), and which isarrested in a releasing/pivoting position within its working chamber(20) when a defined value of hydraulic pressure medium pressure isexceeded.
 2. A locking device according to claim 1, characterized inthat each wing (13) of the winged wheel (9) configured as a lockingelement is arranged for radial movement within its axial groove (12) inthe wheel hub (11) of the winged wheel (9) and a free end (14) of saidwing is in positive engagement with a corresponding axial fixing groove(23) in the inner surface (5) of the circumferential wall (4) of thedrive pinion (3) in one or more locking positions of the device (1). 3.A locking device according to claim 2, characterized in that only onewing (13) of the winged wheel (9) is configured as a locking element andis in locking connection only in one of its end positions with an axialfixing groove (23) which directly adjoins one of the two intermediatewalls (16) that define its working chamber (20) or pressure chambers(21, 22).
 4. A locking device according to claim 1, characterized inthat the auxiliary energy required for locking the wing (13) in itslocking position is produced by a spring means (24) including coiledcompression springs or leaf springs supported at one end on the groovebottom of the axial groove (12) and at a second end on the hub-proximateend (15) of the wing (13).
 5. A locking device according to claim 1,characterized in that the free end (14) of the wing (13) configured as alocking element is slightly chamfered in radial direction and configuredas a pressure-application surface for the hydraulic pressure medium forthe unlocking position of the wing (13), a separate pressure mediumsupply duct (25) opening into the widened gap thus formed between thefree end (14) of the wing (13) and the groove bottom of the axial fixinggroove (23) and communicating with the pressure medium supply duct (26)of the pressure) chamber (21) of the working chamber (20) in which theaxial fixing groove (23) is arranged.
 6. A locking device according toclaim 5, characterized in that the separate pressure medium supply duct(25) to the free end (14) of the wing (13) constituting the lockingelement is configured in the drive pinion (3) as an edge bevel on one ofthe two lateral edges (17, 18) of the intermediate wall (16) adjoiningthe axial fixing groove (23) and defining the pressure chamber (21). 7.A locking device according to claim 5, characterized in that theseparate pressure medium supply duct (25) to the free end (14) of thewing (13) constituting the locking element is configured as a pressuremedium guide groove on the inner surface of one of the two side walls(6, 7) of the drive pinion (3), said separate pressure medium guidegroove being arranged at a level of and parallel to the lateral surface(19) of the intermediate wall (16) adjoining the axial fixing groove(23) and defining the pressure chamber (21).